DNA as an evidence plays a very important role in establishment of human identity through genetic profiling both in criminal and civil disputes. DNA has emerged as a powerful investigative tool as no two persons can have same DNA profile except for identical twin. The proper collection of any biological samples is must for effective utilization of DNA as medicolegal evidence. Single biological sample such as blood, semen, saliva, and hairs etc without any contamination can easily identify a single person. But, if there is mixing/contamination of the biological samples or there is insufficient sample collection from the object or surface for genetic profiling then the results can be ambiguous. In such situations, reports are inconclusive, also it could be difficult to exclude genetic sample of perpetrator from such mix profile results. Furthermore, the new age treatment therapies such as In-Vitro Fertilization (IVF), Blood transfusion, bone marrow transplantation and organ transplants can also hinder to present the actual identity or genetic profile of a person due to genetic mixing. Therefore, biological samples collected from crime scene can either match with suspect or acquit him/her from suspicion. Modern DNA forensic methods are powerful and sensitive, carelessness or ignorance in proper history and handling procedures for biological evidence can result in an unfit sample for analysis.